Motorcycles have become an extremely popular type of vehicle and have enjoyed widespread use for activities such as sport and recreation as well as general transportation. In addition, certain motorcycles have become the centerpiece of extensive hobby and collector enthusiasts due to the variety of motorcycles manufactured through the years as the technology has developed and improved. In addition, various motorcycles have become the subject of substantial nostalgia and have in some instances come to symbolize certain periods of life or lifestyles to a broad range of individuals. As a result, motorcycles continue to be extremely popular and continue to appeal to an ever broadening consumer base. While the design and appearance of motorcycles have undergone substantial variation and change through the years, all may be generally described as vehicles having a basic frame which supports a rear drive wheel and a pivoting front wheel supported by a pivotable steering assembly having a set of handlebars at the upper portion thereof. A seat is supported upon the frame between the front and rear wheels and suitable supports for the rider's feet are provided at the lower frame. In most motorcycles the engine is positioned generally beneath and usually slightly forward of the seat while the fuel tank is positioned above the engine and extends generally between the seat and the front steering housing.
One of the more popular motorcycles through the years is known as the Harley-Davidson motorcycle manufactured and sold by the Harley-Davidson Motorcycle Company. In many Harley-Davidson motorcycles, the fuel tank is somewhat teardrop shaped defining a larger cross-section at the front portion and tapering to a narrower cross-section at the rear portion. The fuel filler is positioned on the upper surface of the fuel tank and includes a circular aperture having a cylindrical filler neck extending from the upper tank surface into the tank interior. The filler neck defines internal threads within the cylindrical filler neck passage for receiving a gas cap and further defines a raised ring encircling the filler neck aperture and rising slightly above the adjacent tank surface. The gas cap in such motorcycles includes a generally cylindrical externally threaded member having a large circular and often somewhat dome-shaped knob at the top portion thereof. A resilient seal or gasket is supported on the underside of the circular knob at the top of the threaded cylindrical portion. As the knob is threaded into the filler neck, the resilient seal is forced against the raised ring and compresses to provide a sealing closure of the filler neck.
The most common practice in Harley-Davidson motorcycle manufacture and restoration is to paint the fuel tank with a smooth lustrous high gloss paint. The paint applied to the fuel tank extends across and covers the raised ring encircling the filler neck. The presence of this painted surface upon the raised ring causes several problems to arise in the motorcycle during use. For example, the insertion and removal of the service station filler nozzle during refueling often chips and damages the paint upon the raised ring. This provides an uneven surface which reduces the effectiveness of the resilient seal and raises the potential for fuel leakage. In addition, the chipping of the protective paint permits other undesired chemical reactions such as corrosion or rust to take place. In addition to paint chipping due to filler nozzle insertion and removal, the fuel used in such motorcycles is often incompatible with the high luster, high gloss paints used by many enthusiasts. As a result, the paint may blister and flake excessively about the raised fuel ring.
All of these problems combine to create a substantial nuisance in the use of Harley Davidson motorcycles having such filler neck constructions.
There arises therefore a need in the art for appropriate corrective measures and protective apparatus which may be used to overcome these deficiencies in this type of motorcycle fuel tank construction.